Enhance player selection functionality in Handbuilder: allow multi-row selection, track previous selections, and update lineup accordingly. Clear selections on lineup reset.

src/streamlit_app.py

@@ -616,20 +616,33 @@ if selected_tab == 'Handbuilder':
     handbuilder_lineup_build_column, handbuilder_player_select_column = st.columns([1, 2])
     with handbuilder_player_select_column:
         st.subheader("Player Select")
+        dataframe_key = f"player_select_dataframe_{st.session_state.get('dataframe_key_counter', 0)}"
+        
         event = st.dataframe(
             st.session_state['player_select_df'].style.background_gradient(axis=0).background_gradient(cmap='RdYlGn').background_gradient(cmap='RdYlGn_r', subset=['Salary', 'Own']).format(precision=2),
             on_select="rerun",
-            selection_mode=["single-row"],
-            key="player_select_dataframe",
+            selection_mode="multi-row",
+            key=dataframe_key,
             height=500,
             hide_index=True
         )
-        # If a row is selected, add that player to the lineup and reset selection
-        if event and "rows" in event.selection and len(event.selection["rows"]) > 0:
-            idx = event.selection["rows"][0]
+        
+        # Get current selection state
+        current_selection = set()
+        if event and "rows" in event.selection:
+            current_selection = set(event.selection["rows"])
+        
+        # Get previous selection state from session
+        previous_selection = set(st.session_state.get('previous_player_selection', []))
+        
+        # Find newly selected and newly unselected players
+        newly_selected = current_selection - previous_selection
+        newly_unselected = previous_selection - current_selection
+        
+        # Handle newly selected players (add to lineup)
+        for idx in newly_selected:
             player_row = st.session_state['player_select_df'].iloc[[idx]]
             eligible_positions = re.split(r'[/, ]+', player_row['Position'].iloc[0])
-            # Find the first eligible slot that is not full
             slot_to_fill = None
 
             for slot in ['QB', 'RB', 'WR', 'TE', 'UTIL', 'DST']:
@@ -645,13 +658,22 @@ if selected_tab == 'Handbuilder':
             if slot_to_fill is not None:
                 # Avoid duplicates
                 if not player_row['Player'].iloc[0] in st.session_state['handbuilder_lineup']['Player'].values:
-                    # Add the slot info
                     player_row = player_row.assign(Slot=slot_to_fill)
                     st.session_state['handbuilder_lineup'] = pd.concat(
                         [st.session_state['handbuilder_lineup'], player_row[['Player', 'Position', 'Team', 'Salary', 'Median', '2x%', 'Own', 'Slot']]],
                         ignore_index=True
                     )
-
+        
+        # Handle newly unselected players (remove from lineup)
+        for idx in newly_unselected:
+            player_to_remove = st.session_state['player_select_df'].iloc[idx]['Player']
+            if player_to_remove in st.session_state['handbuilder_lineup']['Player'].values:
+                st.session_state['handbuilder_lineup'] = st.session_state['handbuilder_lineup'][
+                    st.session_state['handbuilder_lineup']['Player'] != player_to_remove
+                ]
+        
+        # Store current selection for next comparison
+        st.session_state['previous_player_selection'] = list(current_selection)
 
     with handbuilder_lineup_build_column:
         st.subheader("Lineup Build")
@@ -696,26 +718,13 @@ if selected_tab == 'Handbuilder':
 
         st.session_state['lineup_display_df'] = pd.DataFrame(display_rows, columns=display_columns)
 
-        # Show the lineup table with single-row selection for removal
-        event_remove = st.dataframe(
+        # Show the lineup table as a static display (no selection needed)
+        st.dataframe(
             st.session_state['lineup_display_df'].style.background_gradient(axis=0).background_gradient(cmap='RdYlGn', subset=['Median']).background_gradient(cmap='RdYlGn_r', subset=['Salary', 'Own']).format(precision=2),
-            on_select="rerun",
-            selection_mode=["single-row"],
-            key="lineup_remove_dataframe",
             height=445,
             hide_index=True
         )
 
-        # If a row is selected and not blank, remove that player from the lineup
-        if event_remove and "rows" in event_remove.selection and len(event_remove.selection["rows"]) > 0:
-            idx = event_remove.selection["rows"][0]
-            player_to_remove = st.session_state['lineup_display_df'].iloc[idx]['Player']
-            slot_to_remove = st.session_state['lineup_display_df'].iloc[idx]['Slot']
-            if player_to_remove:  # Only remove if not blank
-                st.session_state['handbuilder_lineup'] = filled_lineup[
-                    ~((filled_lineup['Player'] == player_to_remove) & (filled_lineup['Slot'] == slot_to_remove))
-                ]
-
         # --- SUMMARY ROW ---
         if not filled_lineup.empty:
             total_salary = filled_lineup['Salary'].sum()
@@ -781,6 +790,11 @@ if selected_tab == 'Handbuilder':
     with clear_col:
         if st.button("Clear Lineup", key='clear_lineup_button'):
             st.session_state['handbuilder_lineup'] = pd.DataFrame(columns=['Player', 'Position', 'Team', 'Salary', 'Median', '2x%', 'Own', 'Slot'])
+            # Clear the dataframe selections by resetting the previous selection state
+            st.session_state['previous_player_selection'] = []
+            # Force dataframe to re-render with new key to clear selections
+            st.session_state['dataframe_key_counter'] = st.session_state.get('dataframe_key_counter', 0) + 1
+            st.rerun()
     with save_col:
         if st.button("Save Lineup", key='save_lineup_button'):
             if 'saved_lineups' in st.session_state: